U.S. patent application number 14/513483 was filed with the patent office on 2015-04-23 for system and method for heat storage in solar thermal power plants.
The applicant listed for this patent is KRISHNA KUMAR BINDINGNAVALE RANGA. Invention is credited to KRISHNA KUMAR BINDINGNAVALE RANGA.
Application Number | 20150107246 14/513483 |
Document ID | / |
Family ID | 52824952 |
Filed Date | 2015-04-23 |
United States Patent
Application |
20150107246 |
Kind Code |
A1 |
BINDINGNAVALE RANGA; KRISHNA
KUMAR |
April 23, 2015 |
SYSTEM AND METHOD FOR HEAT STORAGE IN SOLAR THERMAL POWER
PLANTS
Abstract
The embodiments herein provide an improved method for storing
thermal energy from the sun in a CSP plant. The heat storage system
used for storing the thermal energy has a spherical shell filled
with a salt, and several insulated storage towers. The method for
storing thermal energy comprises adopting a plurality of spherical
shells and filling the spherical shells with the salt. The salt is
a mixture of sodium nitrate and potassium nitrate. The spherical
shells filled with the salt are packed inside the insulated storage
tower. During the day time, a HTF is passed through the tower to
melt the salt and store thermal energy. After sunset, the HTF is
passed through the storage tower to absorb heat from the salt in
the spherical shells. The HTF is then passed through the boiler for
producing steam and driving, the turbine.
Inventors: |
BINDINGNAVALE RANGA; KRISHNA
KUMAR; (BANGALORE, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BINDINGNAVALE RANGA; KRISHNA KUMAR |
BANGALORE |
|
IN |
|
|
Family ID: |
52824952 |
Appl. No.: |
14/513483 |
Filed: |
October 14, 2014 |
Current U.S.
Class: |
60/641.15 ;
126/619; 126/714 |
Current CPC
Class: |
F28D 20/023 20130101;
Y02E 10/46 20130101; F28D 2020/0047 20130101; Y02E 60/14 20130101;
Y02E 70/30 20130101; Y02E 60/145 20130101; F03G 6/067 20130101;
F03G 2006/008 20130101 |
Class at
Publication: |
60/641.15 ;
126/619; 126/714 |
International
Class: |
F24J 2/34 20060101
F24J002/34; F03G 6/06 20060101 F03G006/06 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 18, 2013 |
IN |
1723/CHE/2013 |
Claims
1. A system for storing thermal energy in a concentrated solar
thermal power plant comprising: a plurality of insulated storage
towers configured for storing a thermal energy obtained from sun; a
plurality of spherical shells filled with a salt substance, wherein
the solar towers hold the plurality of spherical shells; a fluid
circulating tube for carrying a Heat Transfer Fluid (HTF); wherein
the HTF is configured to carry heat generated from a solar energy
between the plurality of solar towers to a heat exchanger, and
wherein the salt substance is used to capture heat from the
HTF.
2. The system according to claim 1, wherein the salt substance is
eutectic mixture of salts with appropriate melting point.
3. The system according to claim 1, wherein the solar towers are
insulated to avoid a dissipation of the stored thermal energy from
the spherical shells to the surroundings.
4. The system according to claim 1, wherein a plurality of voids
are formed between the plurality of spherical shells, and wherein
the voids allow the flow of the HTF though the tower to an outlet
of the thermal power plant.
5. The system according to claim 1, wherein the spherical shells
comprise a plurality of fins, and wherein the fins are protrusions
formed on a outer surface of the spherical shells, wherein the
plurality of fins assists heat transfer between the HTF and the
salt substance inside the spherical shells.
6. The system according to claim 1, wherein the concentrated solar
thermal power plant comprises a solar field for collecting and
concentrating a plurality of sun rays, and wherein the concentrated
sun rays are directed to is the solar towers by a plurality of
mirrors
7. The system according to claim 1, wherein the fluid circulating
tube is placed at the focusing point of the solar field, and
wherein the plurality of sun rays are concentrated on the fluid
circulating tube for transferring heat from the sun rays to the HTF
in the tube and in-turn the heat from HTF is transferred to the
salt substance, as the HTF passes through the solar towers.
8. The system according to claim 1, wherein the HTF is passed
through the plurality of storage towers for melting the salt in the
plurality of spherical shells, and wherein the molten salt inside
the plurality of spherical shells is configured for storing the
thermal energy from heat absorbed.
9. The system according to claim 1, wherein the HTF is passed
through the storage tower for absorbing the heat from the spherical
shells, wherein the HTF is adopted for absorbing the heat from the
molten salt in the spherical shells.
10. The system according to claim 1, wherein the flow of HTF
through the tower is continued till the solar energy is available
and wherein the thermal energy from the molten salt is utilized
when the solar energy is unavailable.
11. The system according to claim 1, wherein the thermal energy
from the molten salt is used to operate steam turbines and generate
electricity.
12. A method for storing the thermal energy in solar thermal power
plant comprising steps of: installing a solar field adjacent to the
solar thermal power plant; packing a plurality of spherical shells
filled with the salt inside a insulated storage tower; passing a
HTF such as oil, through a fluid circulating tube; circulating the
HTF to a storage tower packed with a plurality of spherical shells;
transferring the heat from the HTF to the salt material in the
spherical shells; absorbing the transferred heat from the molten
salt to the HTF, when the solar energy is not available; and
operating a steam turbine using the thermal energy from the
HTF.
13. The method according to claim 12, wherein the HTF is passed
through the solar field and is heated by the incident sun rays.
14. The method according to claim 12, wherein the HTF is then
passed through the towers for melting the salt in the spherical
shells, and wherein the molten salt inside the spherical shell
stores the thermal energy from the sun rays.
15. The method according to claim 12, wherein the heat transfer
fluid (HTF) is passed through the storage tower again when the
solar energy from sun rays is not available, and wherein the HTF
circulated for absorbing the heat from the spherical shells, and
wherein the HTF drips down on the surface of the spherical shells
and absorbs the heat.
16. The method according to claim 12, wherein the HTF is then
passed through the boiler for producing steam which drives the
steam turbine for generating electric power.
17. The method according to claim 12, wherein the filling of the
salt material in the spherical shells are evacuated in a manner to
avoid any air pockets.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This patent application claims the priority of the Indian
Provisional Patent Application No. 1723/CHE/203 filed on Apr. 18,
2013, and postdated to Oct. 18, 2013 with the title "A Method for
Heat Storage in Solar Thermal Power Plants", and the content of
which is incorporated in entirety by reference herein,
BACKGROUND
[0002] 1. Technical Field
[0003] The embodiments herein generally relate to the field of
electrical power generation through solar thermal power and
particularly relates to a method and a system for storing the solar
thermal energy in a solar thermal power plant. The embodiments
herein more particularly relates to a system and method for
improving the solar thermal energy storage capacity by employing a
molten salt in a concentrated solar thermal power plant.
[0004] 2. Description of the Related Art
[0005] The solar thermal power plants harness the radiant energy of
the sun to produce electricity. A typical Concentrated Solar
Thermal Power (CSP) plant consists of a large number of mirrors
which concentrate the radiant energy of the sun onto the tubes
carrying a heat transfer fluid (HTF). This HTF transfers the
absorbed heat to water through a heat exchanger. The water is
converted into steam and is used to drive a steam turbine-generator
set for generating electric energy. The CSP power plants however
suffer from the same problem that all the solar thermal based
systems have to deal with; the changing position of the sun.
Because of the changing position of sun, the radiant energy of the
sun is never constant throughout the day and the power is produced
only till the sun is out. To producing power continuously even
after the sun is set, technologies have been developed to store the
thermal energy of the sun. There are several methods to store the
thermal energy such as water storage, packed bed storage systems,
storage walls, thermocline systems and molten salt based
systems.
[0006] According to the existing methods, the most popular way of
storing the thermal energy is the usage of molten salt to absorb
the heat of the sun rays. This process involves heating a salt
material till the melting temperature and then storing the molten
salts in the tanks. A separate tank is used for storing the hot and
cold salts. The hot molten salt is then used to produce steam in a
steam generator, which is then used to drive a steam
turbine-generator set for generating a power. The molten salt is
directly pumped to the heat exchangers for generating the steam.
Though, this process enables the production of energy after the sun
is set, the molten salt requires two tanks for storage, one for hot
and another for cold salt. Also, there are chances of the pumped
molten salt being frozen during the passage of the salt to the heat
exchangers or in any other part and thereby blocking the flow and
the power plant operation.
[0007] Hence, there is a need for an improved method and a system
for storing the thermal energy using the molten salt in the solar
thermal power plant. Also, there is a need for a method and a
system to improve the thermal storage capacity of molten salt in
solar thermal power plants. Further there is a need for method and
a system for handling the molten salts.
OBJECTIVES OF THE EMBODIMENTS
[0008] The primary objective of the embodiments herein is to
provide a thermal storage system for storing the thermal energy of
the sun and a method for using the stored energy after the
sunset.
[0009] Another objective of the embodiments herein is to provide a
method to simplify the thermal energy storage system.
[0010] Yet another objective of the embodiments herein is to
provide a method for improving the thermal energy storage by means
of a molten salt tower packing.
[0011] Yet another objective of the embodiments herein is to
provide a method to prevent a freezing of the molten salt during
circulation.
[0012] These and other objects and advantages of the embodiments
herein will become readily apparent from the following detailed
description taken in conjunction with the accompanying
drawings.
SUMMARY
[0013] The embodiments herein provide an improved method and system
for storing thermal energy from the sun in a concentrated solar
thermal power plant. The heat storage system for storing the
thermal energy of the sun comprises a plurality of insulated
storage towers configured for storing a thermal energy obtained
from sun and a plurality of spherical shells filled with a salt
substance. The solar towers hold the plurality of spherical shells.
The system further comprises a fluid circulating tube for carrying
a Heat Transfer Fluid (HTF). The HTF is configured to carry heat
generated from a solar energy between the plurality of solar towers
to a heat exchanger. The salt substance is used to capture heat
from the HTF.
[0014] According to one embodiment herein, the salt substance is
eutectic mixture of salts with appropriate melting point.
[0015] According to one embodiment herein, the solar towers are
insulated, to avoid a dissipation of the stored thermal energy from
the spherical shells to the surroundings.
[0016] According to one embodiment herein, a plurality of voids is
formed between the plurality of spherical shells. The voids allow
the flow of the HTF through the tower to an outlet of the thermal
power plant.
[0017] According to one embodiment herein, the spherical shells
comprise a plurality of fins, where the fins are protrusions formed
on the outer surface of the spherical shells. The plurality of fins
assists in an effective heat transfer between the HTF and the salt
substance inside the spherical shells.
[0018] According to one embodiment herein, the concentrated solar
thermal power plant comprises a solar field for collecting and
concentrating a plurality of sun rays. The concentrated sun rays
are directed to the solar towers by a plurality of mirrors,
[0019] According to one embodiment herein, the fluid circulating
tube is placed at the focusing point of the solar field, wherein
the plurality of sun rays are concentrated on the fluid circulating
tube for transferring heat from the sun rays to the HTF in the tube
and in-turn the heat from HTF is transferred to the salt substance,
as the HTF passes through the solar towers.
[0020] According to one embodiment herein, the. HTF is passed
through the plurality of storage towers for melting the salt in the
plurality of spherical shells. The molten salt inside the plurality
of spherical shells is configured for storing the thermal energy
from heat absorbed.
[0021] According to one embodiment herein, the HTF is passed
through the storage tower to absorbing the heat from the spherical
shells. The HTF is adopted for absorbing the heat from the molten
salt in the spherical
[0022] According to one embodiment herein, the flow of HTF through
the tower is continued till the solar energy is available and the
thermal energy from the molten salt is utilized even, when the
solar energy is unavailable.
[0023] According to one embodiment herein, the thermal energy from
the molten salt is used to operate steam turbines and generate
electricity.
[0024] The various embodiments herein provide, a method for storing
the thermal energy in solar thermal power plant. The method
comprises steps of installing a solar field adjacent to the solar
thermal power plant. A plurality of spherical shells filled with
the salt is packed inside an insulated storage tower. HTF such as
oil, is passed through a fluid circulating tube. The HTF is
circulated to a storage tower packed with a plurality of spherical
shells. The heat is transferred from the HTF to the salt material
in the spherical shells. The transferred heat is absorbed from the
molten salt to the HTF, when the solar energy is not available. A
steam turbine is operated using the thermal energy from the
HTF.
[0025] According to one embodiment herein, the HTF is passed
through the solar field and is heated by the incident sun rays.
[0026] According to one embodiment herein, the HTF is then passed
through the towers for inciting the salt in the spherical shells.
The molten salt inside the spherical shell stores the thermal
energy from the sun rays.
[0027] According to one embodiment herein, the heat transfer fluid
(HTF) is passed through the storage tower again when the solar
energy from sun as is not available. The HTF circulated for
absorbing the heat from the spherical shells. The HTF drips down on
the surface of the spherical shells and absorbs the heat.
[0028] According to one embodiment herein, the HTF is then passed
through the boiler for producing steam which drives the steam
turbine for generating electric power.
[0029] According to one embodiment herein, the filling of the salt
material in the spherical shells are evacuated in a manner to
avoid, any air pockets.
[0030] These and other aspects of the embodiments herein will be
better appreciated and understood when considered in conjunction
with the following description and the accompanying drawings. It
should be understood, however, that the following descriptions,
while indicating the preferred embodiments and numerous specific
details thereof, are given by way of an illustration and not of a
limitation. Many changes and modifications may be made within the
scope of the embodiments herein without departing from the spirit
thereof, and the embodiments herein include all such
modifications.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] The other objects, features and advantages will occur to
those skilled in the art from the following description of the
preferred embodiment and the accompanying drawings in which:
[0032] FIG. 1 illustrates a functional block diagram of a system
for improving the storage capacity of a Concentrated Solar Thermal
Power (CSP) plant, according to one embodiment herein.
[0033] FIG. 2 illustrates a flowchart indicating the steps involved
in a method for storing the thermal energy in solar thermal power
plant, according to one embodiment herein.
[0034] Although the specific features of the embodiments herein are
shown in some drawings and not in others. This is done for the
convenience only as each feature may be combined with any or all of
the other features in accordance with the embodiments herein.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0035] In the following detailed description, a reference is made
to the accompanying drawings that form a part hereof, and in which
the specific embodiments that may be practiced is shown by way of
illustration. These embodiments are described in sufficient detail
to enable those skilled in the art to practice the embodiments and
it is to be understood that the logical, mechanical and other
changes may be made without departing from the scope of the
embodiments. The following detailed, description is therefore not
to be taken in a limiting sense.
[0036] The various embodiments herein provide an improved method
and system for storing thermal energy from the sun in a
concentrated solar thermal power plant. The heat storage system for
storing the thermal energy of the sun comprises a plurality of
insulated storage towers configured for storing a thermal energy
obtained from sun and a plurality of spherical shells filled with a
salt substance. The solar towers hold the plurality of spherical
shells. The system further comprises a fluid circulating tube for
carrying, a Heat Transfer Fluid (HTF). The HTF is configured to
carry heat generated from a solar energy between the plurality of
solar towers to a heat exchanger. The salt substance is used to
capture heat from the HTF.
[0037] According to one embodiment herein, the salt substance is
eutectic mixture of salts with appropriate melting point.
[0038] According to one embodiment herein, the solar towers are
insulated to avoid dissipation of the stored thermal energy from
the spherical shells to the surroundings.
[0039] According to one embodiment herein, a plurality of voids is
formed between the plurality of spherical shells. The voids allow
the flow of the HTF through the tower to an outlet of the thermal
power plant.
[0040] According to one embodiment herein, the spherical shells
comprise a plurality of fins, where the fins are protrusions formed
on an outer surface of the spherical shells. The plurality of fins
assists in an effective heat transfer between the HTF and the salt
substance inside the spherical shells.
[0041] According to one embodiment herein, the concentrated solar
thermal power plant comprises a solar field for collecting and
concentrating a plurality of sun rays. The concentrated sun rays
are directed to the solar towers by a plurality of mirrors.
[0042] According to one embodiment herein, the fluid circulating
tube is placed at the focusing point of the solar field, wherein
the plurality of sun rays are concentrated on the fluid circulating
tube for transferring; heat from the sun rays to the HTF in the
tube and in-turn the heat from HTF is transferred to the salt
substance, as the HTF passes through the solar towers.
[0043] According to one embodiment herein, the HTF is passed
through the plurality of storage towers for melting the salt in the
plurality of spherical shells. The molten salt inside the plurality
of spherical shells is configured for storing the thermal energy
from heat absorbed.
[0044] According to one embodiment herein, the HTF is passed
through the storage tower for absorbing the heat from the spherical
shells. The HTF is adopted for absorbing the heat from the molten
salt in the spherical shells.
[0045] According to one embodiment herein, the flow of HTF through
the tower is continued till the solar energy is available and the
thermal energy from the molten salt is utilized when the solar
energy is unavailable.
[0046] According to one embodiment herein, the thermal energy from
the molten salt is used to operate steam turbines and generate
electricity,
[0047] The various embodiments herein, provide a method for storing
the thermal energy in solar thermal power plant. The method
comprises steps of installing a solar field adjacent to the solar
thermal power plant. A plurality of spherical shells filled with
the salt is packed inside an insulated storage tower. A HTF such as
oil, is passed through a fluid circulating tube. HTF is circulated
to a storage tower packed with a plurality of spherical shells. The
heat is transferred from the. HTF to the salt material in the
spherical shells. The transferred heat is absorbed from the molten
salt to the HTF, when the solar energy is not available. A steam
turbine is operated using the thermal energy from the HTF.
[0048] According to one embodiment herein, the HTF is passed
through the solar field and is heated by the incident sun rays.
[0049] According to one embodiment herein, the HTF is then passed
through the towers for melting the salt in the spherical shells.
The molten salt inside the spherical shell stores the thermal
energy from the sun rays.
[0050] According to one embodiment herein, the heat transfer fluid
(HTF) is passed through the storage tower again when the solar
energy from sun rays is not available. The HTF circulated for
absorbing the heat from the spherical shells. The HTF drips down on
the surface of the spherical shells and absorbs the heat.
[0051] According to one embodiment herein, the HTF is then passed
through the boiler for producing steam which drives the steam
turbine for generating electric power.
[0052] According to one embodiment herein, the filling of the salt
material in the spherical shells are evacuated in a manner to avoid
any air pockets.
[0053] The embodiments herein provide an improved system and method
for storing thermal energy from the sun in a concentrated solar
thermal power plant. The heat storage system for storing the
thermal energy of the sun adopts a plurality of spherical shells
tilled with salt and one or more insulated storage towers. The salt
is eutectic mixture of salts with appropriate melting point. In one
embodiment, the salt is a eutectic mixture of sodium nitrate and
potassium nitrate. The method for storing the thermal energy
comprises the steps of packing a plurality of spherical shells
filled with the salt inside the insulated storage tower. Based on
the requirement, an appropriate number of insulated towers are
constructed and filled with the spherical shells. During the day, a
Heat transfer fluid arm is passed through a solar field and is
heated by the incident sun rays. The HTF is then passed through the
towers and used to melt the salt in the spherical shells. After
sunset, the heat transfer fluid (HTF) is passed through the storage
tower again but for absorbing the heat from the spherical shells.
The HTF is then passed through the boiler for producing steam which
drives the steam turbine, for generating electric power.
[0054] According to one embodiment herein, the heat storage system
for storing thermal energy of the sun comprises a salt, a plurality
of spherical shell and one or more insulated towers. The spherical
shell is filled with a salt material. The filling of the salt
material in the spherical shell is done in a manner to avoid any
air pockets, i.e. spherical shells are evacuated. The salt tilled
spherical shells are packed and sealed to avoid any contamination.
The sealed spherical shells are then stacked in the vertically
placed insulated towers. The insulated towers avoid a dissipation
of the stored thermal energy from the spherical shells to the
surroundings. The heat storage system is scalable due to the usage
of individual spherical shells for storing molten salt. When the
spherical shells are placed inside the tower, voids are formed
between the spherical shells. The voids allow the flow of the HIT
through the tower to the outlet. The spherical shells are provided
with projections/protrusions on the outer surface referred to as
fins. When the flows through the packed tower, the fins of the
spherical shells assist in an effective heat transfer to and from
the HTF.
[0055] According to one embodiment herein, a method for storing
thermal energy of the sun in solar thermal power plant is provided.
The method for storing the thermal energy comprises the steps of
installing a solar field adjacent to an existing solar thermal
power plant. The new solar field is installed only for the purpose
of storing the thermal energy of the sun. The method further
comprises passing a HTF such as oil, through a fluid circulating
tube. The fluid circulating tube is placed at the focusing point of
the solar field panels. The solar field panels concentrate the
incident radiation of the sun to the fluid circulating tube and the
HTF absorbs the heat. The method further comprises, circulating the
HTF to a storage tower packed with a plurality of spherical shells.
The pluralities of spherical shells are filled with the salt. The
method further comprises transferring the heat from the HTF to the
salt material in the spherical shells. The flow of HTF through the
tower packing is continued till the sun sets. The salt material
absorbs the heat from the HTF and changes to a molten state. The
molten salt has the property of retaining the heat for long
periods.
[0056] According to one embodiment herein, a method for generating
power after sunset comprises the steps of forming a heat transfer
loop through the tubes of the storage tower and a heat exchanger
followed by pumping a HTF through the storage tower. The molten
salt inside the spherical shell stores the thermal energy. The HTF
drips down on the surface of the spherical shells and absorbs the
heat. The method further comprises driving the HTF through the heat
exchanger to convert water into steam. The steam then rotates a
steam turbine and generates electric power.
[0057] According to one embodiment herein, the heat storage system
provides a single, separate tower for storing the thermal energy of
to the sun in the Concentrated Solar Thermal Power (CSP) Plant.
Also, the heat storage system easily handles and packages the salt.
The method of storing the thermal energy in the heat storage system
is applicable to all solar based thermal power plants.
[0058] FIG. 1 illustrates a block diagram for improving the storage
capacity of a Concentrated Solar Thermal Power ((TSP) plant,
according to one embodiment herein. The CSP comprises a first solar
field 101 and a second solar field 102 as shown in FIG. 1. The
first solar field 101 is laid out in an open area for collecting
and concentrating the incident sun rays. The first solar field 101
comprises a plurality of mirrors, aligned in a predetermined order.
The plurality of mirrors focuses the incident sun rays towards a
specific point. The plurality of mirrors is any one or a
combination of parabolic troughs, Fresnel type. etc. Alternately,
the pluralities of mirrors are arranged in a manner such that the
incident solar rays (radiations) are directly routed to a solar
tower for generating heat. The generated heat is transferred to a
HTF such as Thermal VP-1 or similar oil. A circulating tube 103 is
placed at the heating point of the mirrors for carrying the HTF
(HTF). The HTF absorbs heat due to the concentrated radiation
focused by the plurality of mirrors onto the circulating tubes 103.
The HTF carries the absorbed heat out of the first solar field 101
through the fluid circulating tubes 103 to a boiler 104. The boiler
104 is a heat exchanging compartment. The heat from the HTF is
transferred to a driving fluid (preferably water) inside the boiler
104. The boiler 104 converts the water into steam and is directed
to a header through a pipe. The header supplies the steam to a
steam turbine 105. The rotor wheel of the steam turbine 105 drives
the flexible coupling which is coupled to a generator 106 for
generating power. The steam flowing to the steam turbine 105 is
controlled by a flow control valve. The steam after passing through
the steam turbine 105 is condensed back to a liquid through a
condenser 106 and is circulated back to the boiler 104. The fluid
used for condensing the steam evaporates due the exchange of heat.
The evaporated fluid is exhausted to the atmosphere through a
cooling tower 107.
[0059] With respect to FIG. 1, the second solar field 102 is
constructed in the same maimer of the first solar field 101. While
the first solar field 101 is used for generating electric power,
the second solar field 102 is used only for storing the thermal
energy of the sun rays. The heat generated by the concentrated
mirror arrangements in the second solar field 102 is transferred to
the HTF. The HTF flows through a fluid circulating tube 109 placed
at the heating point of the mirrors. The HTF absorbs the heat due
to the concentrated radiation focused by the plurality of mirrors
onto the fluid circulating tubes 109. The HTF is circulated through
a storage tower 110. The storage tower 110 is stacked with the
spherical shells which are in turn tilled with a salt. The salt is
generally composed of material with good heat transfer and
retention characteristics, for example, Potassium Nitrate and
sodium nitrate etc. The salt is eutectic mixture of salts with
appropriate, melting point. In one embodiment, the salt is a
eutectic mixture of sodium nitrate and potassium nitrate. The
spherical shell comprises a fin like projections and evacuated and
sealed after being filled with the salt. The salt expands and
contracts inside the spherical shells and also remains
uncontaminated. When the HTF is circulated through the storage
tower 1110, the salt material inside the spherical shells absorbs
the heat and changes to molten state. The molten salt retains the
heat for longer periods. The circulation of HTF through the storage
tower 110 is continued till the sun is set for storing the maximum
possible thermal energy. When the sun is set, the HTF is passed
through the storage tower through a secondary loop 111. Inside the
storage tower 110, the HTF drips down over the spherical shells and
absorb heat from the molten salt. The molten salt transfers the
absorbed heat to the HTF. The HTF is then passed through the boiler
which produces steam to run the steam turbine 105. The steam
turbine 105 runs the generator 106 and generates electric
power.
[0060] FIG. 2 illustrates a flowchart indicating the steps involved
in a method for storing the thermal energy in solar thermal power
plant, according to one embodiment herein. The method comprises
steps of installing a solar field adjacent to the solar thermal
power plant (201). A plurality of spherical shells filled with the
salt is packed inside an insulated storage tower (202). A HTF such
as oil, is passed through a fluid circulating tube (203). The HTF
is circulated to a storage tower packed with a plurality of
spherical shells (204). The heat is transferred from the HTF to the
salt material in the spherical shells (205). The transferred heat
is absorbed from the molten salt to the HTF, when the solar energy
is not available (206). A steam turbine operating using the thermal
energy from the HTF (207).
[0061] The heat storage system provides a single, separate tower
for storing the thermal energy of the sun in the Concentrated Solar
Thermal Power (CSP) Plant. Also, the heat storage system easily
handles and packages the salt. The method of storing the thermal
energy in the heat storage system is applicable to all solar based
thermal power plants.
[0062] The foregoing description of the specific embodiments will,
so fully reveal the general nature of the embodiments herein that
others can, by applying current knowledge, readily modify and/or
adapt for various applications such specific embodiments thought
departing from the to generic, concept, and, therefore, such
adaptations and modifications should and are intended to be
comprehended within the meaning and range of equivalents of the
disclosed embodiments.
[0063] It is to be understood that the phraseology or terminology
employed herein is for the purpose of description and not of
limitation. Therefore, while the embodiments herein have been
described in terms of preferred embodiments, those skilled in the
art will recognize that the embodiments herein can be practiced
with modifications.
[0064] Although the embodiments herein are described with various
specific embodiments, it will be obvious for a person skilled in
the art to practice the embodiments here with modifications.
[0065] It is also to be understood that the following claims are
intended to cover all of the generic and specific features of the
embodiments described herein and all the statements of the scope of
the embodiments which as a matter of language might be said to fail
there between.
* * * * *